Is there a 'has focus' in JavaScript (or j

2019-01-07 08:15发布

Is there something I can do like this (perhap via a plugin)

if ( ! $('form#contact input]').hasFocus()) {
  $('form#contact input:first]').focus();
}

Basically, set focus to the first input, but only if the user has not already clicked into anything?

I know this will work too, but is there anything more elegant?

$(function() {
  var focused = false;
  $('form#contact input]').focus(function() {
    focused = true;
  }); 
  setTimeout(function() {
    if ( ! focused) {      
      $('form#contact input:first]').focus();
    }
  }, 500);
});

10条回答
仙女界的扛把子
2楼-- · 2019-01-07 08:30

Frustratingly difficult to find a solution to this problem considering the solution is actually very simple:

if (document.activeElement == this) {
  // has focus
}

if (document.activeElement != this) {
  // does not have focus
}

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Evening l夕情丶
3楼-- · 2019-01-07 08:35

jQuery 1.6 now has a dedicated :focus selector.

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虎瘦雄心在
4楼-- · 2019-01-07 08:35

No, there isn't.

However, you can simulate it like this:

$(':input')
    .data('focused', false)
    .focus(function() { $.data(this, 'focused', true); })
    .blur(function() { $.data(this, 'focused', false); });
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在下西门庆
5楼-- · 2019-01-07 08:36

I know this is an old question, but may be my solution will help someone :)

since this didnt worked for me:

if ($(this)!=$(document.activeElement)) { ... }

..were "this" is returned from blur function. So i did this:

if ($(document.activeElement).attr("class") != "input_textbox"){ ... }
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可以哭但决不认输i
6楼-- · 2019-01-07 08:38

I had trouble with cletus approach, using jQuery 1.3.2 and Firefox 3.6.8, because the string "a == document.activeElement" was not a valid function.

I fixed it defining a function for the focus key. In fact, all other keys defined in jQuery.expr[':'] are defined as functions. Here's the code:

jQuery.extend(jQuery.expr[':'], {
    focus: function(e){ return e == document.activeElement; }
});

So, now it works as expected.

However, I was experiencing some strange behaviour in Firefox 3.6.8 (maybe a bug in FF?). If I clicked on an input text while the page was rendering, and if I called is(":focus") on page load, I would get an error from the browser, reported by FireBug, and the script would break.

To solve this, I surrounded the code with a try...catch block, returning false on error. Use it if you want to prevent your users from experiencing the same error:

jQuery.extend(jQuery.expr[':'], {
    focus: function(e){
        try{ return e == document.activeElement; }
        catch(err){ return false; }
    }
});
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Luminary・发光体
7楼-- · 2019-01-07 08:40

$('input:focus')

It's CSS. You don't need to create a "custom selector." It already exists! http://www.w3schools.com/CSS/pr_pseudo_focus.asp

Just attach whatever process you want to do to that selector, and it will weed it out if the element in question is not focused. I did this recently to keep a keyup from instantiating an email input error check when the e-mail input wasn't being used.

If all you're trying to do is check if the user has focused on anything themselves, just do this:

if($('input:focus').size() == 0){
    /* Perform your function! */
}
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